How does Switcheroo work with Blue Rumble ability and Legend?

To understand how Switcheroo interacts with Rumble (specifically the Mechanized Menace Legend and Rumble, Scrapper), we must look at how Might modifiers and passive abilities like Shield function during a swap.

1. The Core Interaction: Switcheroo

According to Rule 420.1 and FAQ #8531, Switcheroo does not "swap" the raw Might values themselves; it calculates the difference between the two units' current Might (including all active buffs, equipment, and passive bonuses) and applies a persistent modifier to each unit to reach the other's total.

• Snapshotting: When Switcheroo resolves, it snapshots the current Might of both units.
• Modifiers: It applies a fixed +X or -X modifier to each unit that lasts until the end of the turn.
• Future Changes: If a unit's Might changes after the swap (e.g., a new buff is applied), that change is calculated on top of the modifier applied by Switcheroo.

2. Interaction with Rumble's Abilities

Rumble provides passive Might bonuses to Mechs via two sources:

• Mechanized Menace (Legend): Grants Mechs Shield (which provides +1 Might while they are a defender).
• Rumble, Scrapper (Unit): Grants Mechs (including himself) +1 Might.

How they interact with Switcheroo:

• Shield (Passive): As clarified in FAQ #8532, Switcheroo counts Shield when it resolves because Shield is a passive effect that contributes to a unit's current Might while they are a defender. Switcheroo snapshots the total Might (including the +1 from Shield) and swaps those totals. The Shield keyword itself remains on the original unit; it does not transfer.
• Rumble, Scrapper's +1 Might: This is a continuous passive bonus. Because it is part of the unit's current Might at the time of resolution, it is included in the calculation for the Switcheroo modifier.

Example Scenario

If you have a Mech unit (Unit A) with 2 base Might and a Rumble, Scrapper in play (granting +1 Might), and another unit (Unit B) with 5 Might:

1. Current State: Unit A has 3 Might (2 base + 1 from Rumble). Unit B has 5 Might.
2. Resolution: Switcheroo calculates the difference (2). It applies a +2 modifier to Unit A and a -2 modifier to Unit B.
3. Result: Unit A now has 5 Might (2 base + 1 Rumble + 2 Switcheroo). Unit B now has 3 Might (5 - 2).
4. If Unit A is a defender: If Unit A also has Shield (from the Mechanized Menace Legend), it would have had 4 Might before the swap (2 base + 1 Rumble + 1 Shield). Switcheroo would have seen 4 and 5, applied a +1 modifier to Unit A and a -1 to Unit B. Unit A would end up with 5 Might (2 base + 1 Rumble + 1 Shield + 1 Switcheroo).

Summary: Switcheroo treats Rumble's passive bonuses and Shield as part of the unit's "current Might" at the moment of resolution. It creates a fixed modifier for the turn based on those totals, but the passive abilities themselves remain on their original units and continue to apply to the new Might totals.

Note: I could not fully verify this ruling against the retrieved rules.